Electron discharge apparatus



Nov.30,1948. H, FO KEg 2,454,786

ELECTRON DISCHARGE APPARATUS Filed Noir. 20, 1943 ii gvento I Patented Nov. 30, 1948 ELECTRON DISCHARGE APPARATUS Christopher Henry Foulkes, London, England, assignor to Standard Telephones and Cables Limited, London, England, a British company Application November 20, 1943, Serial No. 511,099 In Great Britain July 17, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires July 17, 1962 Claims. 1

This invention relates to electron discharge apparatus for operation at extremely high frequencies, of the type disclosed in the United States Patent No. 2,320,860 of June 1, 1943, comprising a substantially closed hollow resonator including an outer shell, an inner portion extending between opposite sides of the shell and means for directing electrons across the outer shell and through the inner portion so that electrons in passing from the outer shell to the inner portion of the resonator are controlled in velocity, and in passing from the inner portion to the outer shell collectively yield more energy to the resonato-r than they take from it. In one form disclosed the resonator consisted of a short length of concentric conductor line with closed ends and having aligned diametric slots, and electrodes for passing electrons through theslots to flow completely through the concentric line along a diameter thereof.

According to one feature of the present invention the inner portion of the resonator, which is usually referred to as the drift tube, is constituted by a sheet metal pressing shaped to provide the slot through which the electrons pass. Conveniently, the drift tube consists of two similarly shaped pressings welded together, each pressing being shaped to provide half the slot. Preferably also the pressings are shaped to provide an integral cylindrical base portion adapted to fit within the outer concentric shell of the resonator, and to be welded thereto.

According to another feature of the invention a copper-plated non-magnetic alloy which can be easily de-gassed and welded is used for the fabrication of the resonator in a tube of the type referred to. A nickel-copper alloy containing about 44% nickel is preferably employed for this purpose.

In the accompanying drawings which illustrate a practical embodiment of the invention,

Fig. 1 is a diagrammatic sectional elevation of a portion of a vacuum tube embodying the invention;

Fig. 2 is a sectional elevation at right angles of the tube shown in Fig. 1;

Fig. 3 is a detail view showing the drift tube detached; and

Fig. 4 is a perspective view of a metal pressing for the drift tube.

The construction and operation of the vacuum discharge tube will be readily understood with reference to the accompanying drawing in which it will be seen that the resonator comprises an outer tube A and an inner concentric portion or drift tube B with a slot C extending through it in line with the diametrically arranged slots in the tube A provided with fins D and E. The anode is indicated at F, the grid at G and the cathode at H. The resonator structure is suitably mounted in an evacuated glass envelope I terminating in a metal cap J in contact with the resonator tube A and to which the metal disc K is soldered, and a central conductor L sealed in a glass cap M is connected to the drift tube through the flexible metal connection N.

Referring now more particularly to Fig. 3 and 4, it will be seen that the drift tube B is constituted by two sheet metal pressings each formed as shown in Fig. 4 with an off-set or channel portion C intermediate the ends of the pressing forming half the width of the slot C, and a semicylindrical end portion or skirt 0 on a semicircular integral fiange, so that when the two similar pressings are welded together they form the complete drift tube structure as shown in Fig. 3, the cylindrical portion 0 fitting within the outer resonator tube A to which it is welded, and the flexible metal connection N welded between the two pressings, being connected tothe central conductor L. The stem portion may be provided with pressed-out strengthening ribs P as shown. The two halves of the drift tube might be formed as one integral pressing bent over at the centre.

We have found that a suitable material for the construction of the drift tube pressings, the resonator tube A, and also for the flexible metal connection N, is a nickel-copper alloy containing about 44% nickel and marketed under the trade name of Ferry. This is a non-magnetic alloy which can be readily de-gassed and welded to form the required structure. It may be copperplated either before or after fabricating the parts, in order to reduce high frequency resistance. The outer concentric tube A may be formed in accordance with United States patent application, Serial No. 457,795, filed September 9, 1942, by Goodchild et a1, granted on October 12, 1948, as Patent Number 2,451,328.

References herein to pressing are intended to refer to a method of shaping metal by the application of pressure, such as stamping, and to metal shapes produced by such processes.

It will be seen, therefore, that the present invention provides a simplified construction of apparatus, since the costly machined drift tube is replaced by a simple pressing, and by the use of the nickel-copper alloy mentioned, the whole assembly may be welded together instead of being 3 riveted as was necessary when using copper for the resonator.

What is claimed is:

1. A resonator structure having a bunching zone, a catching zone and an intermediate drift space, and a drift tube structure surrounding the drift space, including co-extensive abutting fiat metal sections having registering integral off-set portions forming the drift tube.

2. A structure as set forth in claim 1 in which said drift tube structure includes a tubular mount ing element integral with said sections.

3. A structure as set forth in claim 1 in which the sections are of fiat metal of substantially uniform thickness shaped by pressing, each section including an upper re-entrant channel portion forming one-half of the drift tube, .a lower laterally projecting mounting portion, and an integral web connecting said upper and lower portions.

4.- A velocity modulated electron discharge tube comprising an anode, a cathode, and a resonator structure therebetween having a bunching zone, a catching zone and an intermediate drift space,

and a drift tube structure surrounding the driftspace, including complementary abutting sections having registering integral off-set portions forming the drift tube, said sections being made from a non-magnetic alloy that is readily pressed, de-gassed and welded.

5. A tube as set forth in claim 4 in which said alloy is a nickel-copper alloy containing about 44% nickel.

6. A drift tube structure for velocity modulated electron discharge tubes comprising complemen-' tary abutting sections having registering channels forming the drift tube, each section being of flat metal of substantially uniform thickness adaptedto be shaped by pressing.

7. A velocity modulated electron discharge tube comprising an anode, and a spaced cathode, a tubular resonator body having openings between and aligned with said anode and cathode for the passage of an electron beam, and a member having a body portion inside and spaced from the resonator body forming bunching and catching zones and provided with a passage forming a drift tube in alignment with said openings, said member having an integral tubular portion telescoped into and rigidly connected to the resona- 4 tor body at one side of the drift tube and being unsupported and free at the othergside of the drift tube.

8. A resonatorstructure .of the concentric line type for avelocity, modulated electron discharge tube comprising a tubular body having diametrically opposed longitudinal openings for the passage of an electron beam, an inner member extending longitudinally in and spaced from the body, ,having. a drifttube passage in alignment with said openings and including a base engaging said. body, the end of said inner member opposite to the base being free for movement within the body, aniievacuated envelope enclosing the tubular body, an insulated lead extending through the envelope anda yieldable lead connecting the free-:endof the inner member with the insulated lead.

9;Adr'ift-tube structure, for velocity modulated electron beams, comprising two elongated flattened strips of workable-metal, eachstriphaving an off-set stamped intermediate-the ends of the strip; and each strip having atone-enda semi-circular flange extendihg'laterally from onesid'eof the strip, the edge ofthe flange being extended parallel to the strip to form a semicylindricalskir-t; the flattened sides of the two strips being joined together With 'the ofiset'portion and the flanges in' registry.

10. A tube-as set forth in claim '7, wherein said body portion of said member is mounted coaxially inside said reson'ator body, forming therewith a resonator'of the concentric line type.

CHRISTOPHER HENRY FOULKES.

REFERENCES. CITED;

The following references 'are'of record in the fileof this patent:

UNITED STATES PATENTS,

Number Name Date 1,7655605: Mouromtseff June 24, 1930 2,0-74,25'3 Dall'enbach Mar; 16, 1937 21701657" Herzog Aug. 22, 1939 2,173,679 Clark et a1; Sept. 19, 1939 2,190,511 Cage Feb." 13, 1940 2,289,770 Fremlin July-14, 1942 2320,860 F'r'emlin June 1, 1943 

